1. Field of the Invention
The present invention disclosed in this specification relates to a method for manufacturing a semiconductor device. In particular, the present invention relates to a method for manufacturing a semiconductor device in which an element layer is peeled off a supporting substrate by using a peeling layer provided between the supporting substrate and the element layer.
2. Description of the Related Art
In recent years, development of a wireless chip that transmits and receives data has been actively advanced. The wireless chip is also referred to as an IC tag, an ID tag, an RF (Radio Frequency) tag, an RFID (Radio Frequency Identification) tag, a wireless tag, an electronic tag, a wireless processor, a wireless memory, and the like. In this specification, the wireless chip may also be referred to as a semiconductor device.
In general, an RFID tag is constituted by an antenna and an IC chip, which is formed by an element layer including a transistor or the like provided over a silicon wafer. In recent years, however, technological development of an RFID tag using an element layer provided over a glass substrate or the like has been advanced for cost reduction. However, in the case of using a technique for providing an element layer over a glass substrate, after forming an element layer over a glass substrate, the element layer is required to be separated from the glass substrate, which is a supporting substrate, and to displace the element layer over a flexible substrate. The wireless chip is used by attaching to a surface of an article, embedding in an article, or the like so as to be fixed. This is because it is desirable that the wireless chip itself has flexibility in a case of attaching or fixing the wireless chip to an article having curvature or flexibility.
Various techniques are known as a method for peeling an element layer provided over a supporting substrate. For example, there are a method for taking out an element layer by making a supporting substrate thin by grinding or polishing, a method for removing a supporting substrate by chemical reaction or the like, a method for peeling an element layer provided over a supporting substrate, and the like. As a method for peeling an element layer provided over a supporting substrate, there is a method that a separating layer is provided between a substrate and a layer to be transferred, and separation is made to occur in the separating layer by laser light irradiation through the substrate (see Reference 1: Japanese Patent Application Laid-Open No. H10-125929). In addition, there is a method to separate an element layer from a supporting substrate by providing a peeling layer containing silicon between the element layer and the supporting substrate and removing the peeling layer with the use of gas containing halogen fluoride (chemical formula: XFn (X is halogen other than fluorine and n is an integer number) (see Reference 2: Japanese Patent Application Laid-Open No. H8-254686).
However, the above conventional methods, that is, the methods for removing a supporting substrate by grinding, polishing, or dissolving has caused problems such as damage due to physical strength such as stress, and contamination. In addition, according to such methods, it has been extremely difficult to reuse a substrate and the cost has been increased.
In the case where an element layer provided over a supporting substrate is separated by removing a peeling layer provided between the supporting substrate and the element layer, the quality of the peeling layer becomes important. Time required for removing the peeling layer is affected depending on a material used for the peeling layer and an etchant used for removing the peeling layer. In addition, in a case where an element layer constituted by a thin film transistor or the like is provided over a peeling layer, the property of the transistor may be affected and the reliability of a semiconductor device may be decreased depending on a material or the film quality of the peeling layer.